[Solved] Painting - how is the value calculated?

[Kezeal]

EDIT: The Extra Creative modifier multiplies the entire value, including the bonus value from the amount of paintings. Updated information can be found at https://sims.fandom.com/wiki/Painting#Painting_value_and_quality

Based on https://sims.fandom.com/wiki/Painting I made a simple formula in a spreadsheet to calculate how much I should be earning for paintings. I made 318 sketches, and it became obvious that they don't actually boost neither sketching nor painting values as the next painting I made was worth only 839 (and a masterpiece at that).

Now I made a Brilliant Small painting that is worth 1750 simoleons, and it's my 303rd painting. Based on the wiki information the maximum a Brilliant painting could be worth would be:
280 (base value) * 1.25 (highest random modifier) * 1.25 (Brilliant quality) * 1.3 (Master Painter) * 1.5 (Extra Creative) + 2 * 303 (amount of small paintings painted) = 1459.125

Is there something I'm missing in the calculations?

[Trip]

Is your painter a perfectionist or artistic?

[Kezeal]

Artistic, yes. Does that add to the value? All I could find is that it increases how fast you level up the skill. And Perfectionist allegedly only increases chances of Brilliant and Masterpiece (which is overwritten by Extra Creative anyway).

Or is that information false?